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排序方式: 共有287条查询结果,搜索用时 609 毫秒
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Ali Bayram Agah Uguz Ali Durmus 《Journal of Materials Engineering and Performance》2002,11(5):571-576
Three types of material whose fracture toughness tests were previously performed by using circumferentially notched bars,
namely (1) a dual-phase steel with three different morphologies; (2) an Al-Zn-Mg-Cu-wrought alloy; and (3) Al-Si-cast alloys
with three different Si contents, were investigated in terms of accuracy and reliability of the testing method. Also, the
advantages of using circumferentially notched bars for fracture toughness determination of metallic materials were discussed.
With the help of stress concentration factors, which are associated with the bluntness of the notch, correction factors for
the fracture toughness calculations are derived. The corrected fracture toughness values are found to be close to the uncorrected
ones, implying that the testing procedure is reliable. 相似文献
3.
Mustafa Ayhan Erkan Topal 《Tunnelling and Underground Space Technology incorporating Trenchless Technology Research》2005,20(1):81-87
Tunneling projects have their uniqueness in terms of engineering problems. The expertise gained from analyzing these projects establishes a sound basis for future application. This paper conveys experiences gained during the construction and support of the design of the Dicle–Kralkizi water tunnel, Turkey. Tunnel stability problems including overbreaks and surface subsidence are evaluated. An analysis of the breakdowns, factors controlling advance rate and the overall performance of tunnel are covered. The accumulated information presented here is believed to be useful and reliable for a successful tunnel excavation in similar formations. 相似文献
4.
Adem Bayram Murat Kankal Gökmen Tayfur Hızır Önsoy 《Neural computing & applications》2014,24(5):1079-1087
This study investigates use of water quality (WQ) variables, namely total chromium concentration, total iron concentration, and turbidity for predicting suspended sediment concentration (SSC). For this purpose, the artificial neural networks (ANNs) and regression analysis (RA) models are employed. Seven different RA models are constructed, considering the functional relation between measured WQ variables and SSC. The WQ and SSC data are fortnightly obtained from six monitoring stations, located on the stream Harsit, Eastern Black Sea Basin, Turkey. A total of 132 water samples are collected from April 2009 to February 2010. Model prediction results reveal that ANN is able to predict SSC from WQ data, with mean absolute error (MAE) of 10.30 mg/L and root mean square error (RMSE) of 13.06 mg/L. Among seven RA models, the best one, which has the form including all independent parameters, produces results comparable to those of ANN, with MAE = 14.28 mg/L and RMSE = 15.35 mg/L. The sensitivity analysis results reveal that the most effective parameter on the SSC is total chromium concentration. These results have time- and cost-saving implications. 相似文献
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6.
This paper addresses optimal design of simply supported symmetrically laminated composite plates with central circular holes.
The design objective is the maximization of the buckling load, and the design variable is considered as the fiber orientation.
The first-order shear deformation theory is used for the finite element analysis. The study is complicated because the effects
of bending–twisting coupling are also included for the buckling optimization. The modified feasible direction method is used
to solve the optimization problems. Finally, the effect of different number of layers, boundary conditions, width-to-thickness
ratio, plate aspect ratios, hole daimeter-to-width ratio, and load ratios on the results is investigated. 相似文献
7.
The influence of duplex surface treatments consisting of a DC-pulsed plasma nitriding process and subsequent coatings of CrN and TiAlN deposited by physical vapor deposition(PVD)on AISI H13 tool steel was studied in this article.The treated samples were characterized using metallographic techniques,SEM,EDS,and microhardness methods.Hydro-abrasive erosion wear tests were performed in a specifically designed wear tester in which the samples were rotated in a wear tank containing a mixture of distilled water and ceramic abrasive chips with a fixed rotational speed.The wear rates caused by the abrasive particle impacts were assessed based on accumulated weight loss measurements.The worn surfaces were also characterized using optical microscopy,SEM,and EDS.Microhardness measurements indicated a significant increase in the surface hardness of the duplex-treated samples.The surfaces of the samples with the TiAlN coating were approximately 15 times harder than that of the untreated samples and 3 times that of the plasma nitrided samples.Hydro-abrasive erosion wear results showed that the duplex surface treatments,especially the CrN coating,displayed the highest erosion wear resistance. 相似文献
8.
A. Bayram 《Materialwissenschaft und Werkstofftechnik》2004,35(1):29-35
The aim of this study was to investigate the mechanical properties of Al‐Mg‐Si alloys aged to peak hardness with different dispersoid volume fraction. It was found that the tensile strength increases with dispersoid content, for alloys having similar ductility. The effect of an increasingly triaxial stress state on a fracture strain above mentioned alloys were measured using a series of notched tensile specimens whose notch root radius of curvature was changed. The alloy ductility was found to increase with dispersoid content and root radius and to decrease with increased stress triaxiality. The fracture toughness of these alloys was determined as a function of dispersoid content and notch root radius of curvature. It was observed that the fracture toughness increased as the dispersoid content and the notch root radius increased. scanning electron microscope analysis of the fracture surfaces revealed that fracture mechanism was transgranular fracture with dimples formation. It is argued that optimum mechanical properties in these alloys can be achieved at about 0.5 % Mn content. 相似文献
9.
Cemalettin Kubat Harun Taşkin Bayram Topal Safiye Turgay 《Journal of Intelligent Manufacturing》2004,15(4):517-526
Since 1950s the techniques of Operations Research (OR) and Optimization have been utilized to increase the efficiency of the production systems. With the widespread use of computers, it has even become easier to deal with industrial problems. However the complexity of the problems still reveals the difficulty in providing solutions. The use of artificial intelligence (AI) seems to attract the attention of the researcher to overcome to the difficulties. This has already been realized with several successful applications. In this study, the use of AI and OR techniques is compared using fuzzy logic. The progress of manufacturing systems, characteristics of production processes, system managements and system behavior are taken into account. The study is focussed on only discrete manufacturing. 相似文献
10.
Karakus Gulderen Ece Abdulilah Yaglioglu Ayse Sahin Zengin Haci Bayram Karahan Mesut 《Polymer Bulletin》2017,74(6):2159-2184
Polymer Bulletin - Drug carrier, poly(maleic anhydride-co-vinyl acetate) (MAVA or poly[MA-co-VA]) copolymer, was traditionally synthesized by free radical chain polymerization reaction, in methyl... 相似文献